Thank you for the opportunity to help you with your question!
In my personal opinion, a personality trait is an action that a human does subconsciously or a way they act that is repetitive and further becomes such a habit that they are known for that type of action; however, according to scholars, a personality trait is "a person as an embodiment of a collection of qualities" (Dictionary.com). Usually, personality traits are described in reference to a person in the form of an adjective, like nice, happy, or angry in reference to how a person acts in their normal day life.
Please let me know if you need any clarification. I'm always happy to answer your questions.